Fluid motor for reciprocating grease pumps



ugs 7. 1956 l c. c. s. LEcLAiR I 2,757,645

FLUID MOTOR FOR RECIPROCTING GREASE PUMPS Aug 7, 1956 c. c. s. LE CLAIR 2,757,645

FLUID MOTOR FOR REOIPROOATINO GREASE PUMPS Filed May 23, 1951 5 Sheets-Sheet 2 In ventor.'

Aug. 7, 1956 c. c. s. LE CLAIR 2,757,645

FLUID MOTOR FOR REOIPROCATING GREASE PUMPS Filed May 23, 1951 5 Sheets-Sheet 3 A ttom e ys Aug. 7, 195e Filed May 25,

FLUID C. C. S. LE CLAIR MOTOR FOR RECIPROCATING GREASE PUMPS 5 Sheets-Sheet 4 Inventor,

v c. c. su: CLAIR FLUID MOTOR FOR RECIPROCATINO GREASE PUMPS Aug. 7, 1956 Filed May 25, 1951 5 Sheets-Sheet 5 F/GB,

.iwf

v Inventor-r B y I. M a Mi? fl? United States Paterna@ 2,757,645 Pgtented Aug. 7, 195,6

Fig. 6 is a half section onthe line 6-7-6 ,in` Fig.vv 1,

Wilthfparts vshown yin 'elevationy'v This invention relates in generaln to reciprocating' grease 15 or oil or otherliquid pumpsof the type whichfare''a'c-V4 tuated by uid-operated motors'. f The inventionis :particularly applicable to pumps"`of lthev typef'rleferred to f above which areused to pump g'eafseor' foilfor other liquid from containersor drums 'andficbmprise driir'rr'tube's 20 which extend downwardly from'bel'ow thel air-m'cftor into"' the drum and are provided with openings 'throughwh i grease Vor oil 4or other liquid can; pass from't of the drum when thepu'mp` isn"operatin.""Herein" after, for brevity, suchpumps t grease pumps, and grease' or'.

o1 1' otherzlitfid will f be referred to as grease i In known pumpsl of the above mentioned type the", moving pump elements a're directly' coupled tdthe piston of an air-motor, which eitheriincliidesaat r`pi`slt`fo`ln`i30 type fluid-control valve. As such pumpsfhaveftr "stall" when the grease outlet 'is closed th'e'valve'gar have a snap action, the characteristic'ofl wliihis thatwhen the valve operating member "has been pushed vover'dead f centre by the air-motor piston rod, 'it con'tiues'it travel `35 under spring action and completes" the` c':l n ge-over Tof the Valve gear. i One object of the present invention is to provide a reciprocating pump of lthe Vtype referred to con'1`pris' i'ng a high pressure pump which isarrar'rgedv at the Atop of the apparatus nsteadl'of at- `the` bottonr'ofmth'efvgrease suction or drum tube. U A further object of the invention is to pro/videl a reciprocating pump of )the type referredto v'vhichfcorn-y` 4 prises a low pressure grease valvefwhich" also functionsv as a release valve and which-presentsl arelativelylong leakage path for grease and is not easilykprevented fromclosing by the presence ioflforeign bodies in ,the grease.

Another object of the invention-is toreplace the usual -50 spring-controlled iluidfmotor slidegivalvezgear byainag-vv netically-operated valve gear,y which avoids the use 'of precision-made slidevalveswand` glandsmand"which-hals an inherent` snap action dueto the characteristics of. j magnetic fields. -Y .f 1 Y5 And a further object is to provide a new and improved drum pump having a fluid motor, Athe operation of which f e is controlled by a magneticallyoperated"valve gear where` in the operation of thelatter tis controlledby"'reciprocal tion Ufa pump.ptartl.. ,...T I fr t, ...2. Other objects and advantages will become apparent from the following description'taken lcdnjonction with' the accompanying "drawingSfwher "i t Fig. 1 is an outside:elevation'offz fart ofpthepump, with the enclosing housing Vstructure vshown Iiln"s"ec':tion;`

Fig. 2 is a plan yvievvfoftheV 'otorbcylinder fithf the rocker and linkgearfrernoved i" l" Fig. 3 is a section onthey air cylinder of thepumpsho u u y Fig, 4 is a section on'thi1ine'4;4"in"Figt"3; Fig. 5 is a section onth'lin Fig. 7 is ari lis.'or'net1'ic viewof `the linkage connecting the two short-circuitingarmatres; and

Fig.` 8 is' a 'section 1o'n`the line Fig. 4.

Referring to the drawings? This Ypump comprises'an air-motor cylinder 1 whichy l is closed by a top cover 2." '['h'ebaseof'th'e cylinder has a central, downwardly-projecting boss 3 which is` bored toprovide a guid'e`4'fora'holl`w air-motorpiston rod Sand isl collinterbored and threaded at 6 to receive vthe upper end of adu'mtub'el'or'low pressure cylinder 7 which, vwhen the apparatus is in its operative position,

extends downwards throughftheydrurntnotshown) con-v taining the lubricant.

The bottom end of the low pressure cylinder 7 is closed and labove the base the cylinder yis formedwith ainum-Y ber off grease 'inlet ports 8,"Fig. 5,; while.VA above the,V latter the .cylinder is formed withlat least` one `relief port 9. i

The upper end of the, piston rod 5 is fixed in the, sleeve y l. end l() .of.an"upwardly-projecting hollow cylinder 11,.`

which is Aslidably4 guided in abearing 12V, formed centrally in thegairemotor cylinder, cover 2, the air-motor piston 5a, n which is slid fixed to the sleeve end.

; Thel upper end of a which forms part of the said bore yin the` bridge Apiece and is closed at the top by a screwed plug 17,. n', The said end of 'thebore isn'ormallygclosed ,by a check ,valvel 18 which is heldy on itsjseatjby acoil spring 19 reacting between the;l valve and the plug 17..,i A lateral grease* outlet 20 communicates with ,the chambermbetw'eenthe checkvalve 18 4and the plug` 17.

A -hollow high" pressure Vcylinder 21 is slidably arranged on-fthe high pressure piston 13,j"its'lower end" beingclosed by a plug 22 and its upper end being formed with 'a flange 23'whichfis threaded"externallygand is screwed into Van internally threaded retaining sleeve 24 ittedupon the upper endofthe; hollow cylinder 11 fixed f at the upper end of the air-motor piston rod'.

The upper end "of` the'rod 25 (see Fig.` 5) -of a low pressure piston is screwed into the bottom end of the air-r'notorY piston rod 5, and at rits `lower fend it-is integral pressure piston rod 25t'o""ay transversepartition y27fsepa rating'the passage 2.6 froma loweraxialpassage' 28. which extends` downwards from the'parti'tion'toithe lower'face 25h-ofthe 'low'pressurepist-on. `At ,least one radial port 29=is"formed in the low'pressure pistonirodf'ZS belowV thepartition-27 to provide communication between they lower axial passage 28 and"the*exterior of thefrod'and at leastv one radial port 30l is f orrned inthe low pressure piston rod above the partition and is .yadaptedptoprovide the` rod andtheexteriornfof the rod. p

A'sleeve-.t'y'pe valve member2 v upon ythe low`pressure pistn rod 2 for'ced"downwards, slof'that "its bott communication between the upperv axia'rlwpassage 26' 4in thelup'per face of the low 'pressure' piston "2521, by means" in thel sleeve and aI washer 33 slid b1 2;' :fr f '-lw'.: n

ablein a cylinder liner'ld; being A hollow high pressure rpiston 13 is Alxed in .the lower end of thebor'e'of a bridge piece 14.whichnextendslacross, and yis thusdetachablynxed between the upper ends ofptwo vertical bracketslS (see Figs; l and6) which project upwards from the air-motor; cylinder coverv 2.- Thef'upper Yendiofy theV bore 13a of j the high pressure piston 13,-openjs into a chamber 16 31` is slidably arranged the atr-A motor piston rod 5, and a heavier spring 34 which reacts between the washer andan upper washer 35 which is fixed against movement upon the piston rod. The lower end of the valve sleeve 31 is slidable upon an enlargement 36 of the low pressure piston rod, an annular space 37 being formed between the sleeve valve and the reduced part of the pistou rod below a shoulder 31h in the valve. Near its bottom end the sleeve valve is formed with at least one radial port 38, the purpose of which will be described hereinafter.

From the above description it will be understood that when the air-motor is reciprocated the low pressure piston 25a and its piston rod 25, the sleeve valve member 3l, the air-motor piston rod 5 and the cylinder 11 attached to the upper end of the rod and the high pressure cylinder 21 are all reciprocated simultaneously, the high pressure cylinder sliding upwards and downwards over the high pressure piston 13.

Thus, towards the end of the upward stroke of the air-motor piston 5a grease is drawn into the lower end of the drum tube or low pressure cylinder 7 through the grease inlet ports 8 near the bottom end thereof. Towards the end of the downward stroke of the air-motor piston the low pressure piston a moves below the inlet ports 8 and grease is thus trapped between the piston and the closed bottom end 7a of the low pressure cylinder 7. The grease then passes upwards into the lower axial passage 28 in the low pressure piston rod and thence into the annular space 37 between the sleeve valve member 31 and the rod. This annular space constitutes a differential chamber in which the grease pressure acts to force the sleeve valve 31e upwards against the action of the lighter spring 32. The transverse partition 31e in the sleeve valve member thus uncovers the ports 30 in the low pressure piston rod 25 above the transverse partition 30, whereupon grease is transferred from the annular space through the ports 30 into the interior of the airmotor piston rod.

If the grease pressure exceeds a predetermined value, a further upward movement of the sleeve valve member 31 takes place and the upper end of the member contacts the slidable washer 33, and if the grease pressure is sufiiciently high the stronger spring 34 will be compressed and the ports 38 in the valve member will be brought into alignment with the ports 29 in the low pressure piston rod 24 below the transverse partition 27 therein, whereupon excess grease will pass into the annular space around the said rod whence it is discharged back into the grease drum through the relief ports 9 in the drum tube or low pressure cylinder 7.

Thus, the low pressure piston 25a and the drum tube or low pressure cylinder 7 together act as a priming pump to lift grease from the bottom of the drum upwardly through the hollow air-motor piston rod 5. As previously mentioned, the high pressure piston 13 is fixed, so that on the downward stroke of the air-motor piston 5a, the high pressure cylinder 21 is drawn downwards along the piston until the ports 21a in the cylinder are bclow the piston, whereupon grease in the annular space 2lb between the hollow cylinder 11 at the top of the airmotor piston rod and the high pressure cylinder 21 passes into the high pressure piston. This takes place when maximum pressure is developed in the priming pump and this pressure, combined with the partial vacuum produced in the high pressure cylinder 21, causes grease to tiow into the high pressure piston 13.

Upon the commencement of the upward movement of the air-motor piston 5a, the ports 21a in the high pressure cylinder 21 are covered and further upward movement of the cylinder causes grease to be forced upwards through the high pressure piston 13, past the discharge check valve 18 into the bore 16 of the bridge piece 14 and thence into the grease outlet 20.

The supply of compressed air to the air-motor is controlled by two magnetically-operated air valves, one

of'which controls the supply of air to one end of the airmotor cylinder whilst the other controls the exhaust of air from the opposite end of the cylinder. The valves are caused to operate in such a manner that one admits air to its end of the air-motor cylinder whilst the other acts to allow air to be exhausted from the opposite end of the cylinder.

Referring to Figs. 3, 5 and 7, the arrangement includes two at control or short-circuiting armatures or bars 40 and 41 which are arranged on opposite sides of the axis of the air-motor cylinder l. The bases 42 and 42a of actuating links 43 and 43a are mounted upon the top surfaces of the armatures and are held thereon respectively by two coil springs 44 and 45, the springs 44 being arranged around two screws 46 fixed in the armature 40 and the springs 45 around the screws 47 fixed in the armature 41. The link 43 has up-turned ends 48 and 49 (see Fig. 3) and the end 48 is pivotally connected to one end of a rocking beam 50 While the end 49 is pivotally connected to a second rocking beam 51, see Fig. 7. The rocking beams are pivotally supported between their ends by fulcrum pins 52 iournalled in bearings formed in the upstanding-brackets 15 on the airmotor cylinder cover. The beams 50 and 51 are disposed substantially at right angles to the armatures 40 and 41 and they are respectively pivoted to upstanding links 53 and 54, the upper and lower ends of which are connected by cross bars 55 and 56 parallel to the armatures. The upper ends of the vertical links 53 and 54 are respectively connected to arms 57 and 58, the opposite ends of which are fixed to fulcrum pins 59 which are pivotally supported in bearings formed in the upstanding brackets 15.

The two air-control valves 60 and 61, Figs. 3 and 5, are arranged on opposite sides of the air-cylinder axis below the control armatures 40 and 41. The valve 60, which has two needle valve ends 60a and 60h, is fixed in a valve armature or bar 62 arranged in a chamber 63 which is formed in the air-motor cylinder cover 2 below a cover plate 64 fixed thereon, and is connected to the top end of the cylinder by a port 63a, Fig. 3. The valve 61, which has two needle valve ends 61a and 61b, is fixed in a valve armature or bai 65 arranged in a chamber 66 which is formed in the cylinder cover 2 below a cover plate 67 fixed thereto and is connected to the bottom end of the cylinder by a port a shown in Fig. 8. The upper end 60a of the valve 60 is adapted to open and close a valve seat 68 (see Fig. 3) formed in a hollow valve seat member 69 titted in a cavity 70 formed in the cover plate 64. The upper end 61a of the valve 61 is adapted to open and close a valve seat 71 formed in the cover plate 67, the two cavities and 73 being connected by air passages 74 and 75 to the main compressed-air inlet 76 (see Figs. 2 and 6). The bottom end 60h of the needle valve 60 is adapted to open and close a valve seat 77 formed in a hollow valve seat member 78 fitted in a cavity 79 in the air-motor cylinder cover 2.

The bottom end 61b of the needle valve 61 is adapted to open and close a valve seat 80 formed in a hollow valve seat member 81 fitted in a cavity 82 formed in the cover plate 2. The two cavities 79 and 82 are respectively connected by air passages 83 and 84 to exhaust.

Upon the cover plate 64 a permanent magnet 85 (see Figs. 3 and 7) is fixed between two iron blocks 86 and 87 which are formed respectively with holes 88 and 90 which are coaxial with holes 91 and 92 formed in the cover plate 64. Iron pole pieces or rods 93 and 94 are fixed respectively in the coaxial holes so that their inner ends are in the said chamber 63 in the air-motor cylinder cover 2. The pole pieces are arranged directly above the control valve actuating armature 62.

Upon the other cover plate 67, Fig. 7, a permanent magnet 95 is tixed between two iron blocks 96 and 97 which are formed respectively with holes (corresponding to the holes 88 and 90) which are coaxial with holes (corof said rods and into and out of contact therewith, said second bar upon contacting said other ends of said rods short circuiting the magnetic flux of said magnet means to thereby cause said first mentioned bar to move away from said one end of said rods under the action of said biasing means to cause the other of said valve members to block the chamber port it controls.

3. A fluid operated motor comprising a cylinder, a piston reciprocably mounted within said cylinder, a chamber formed in one of the cylinder walls, fluid inlet conduit means leading to said chamber, tluid exhaust conduit means leading from said chamber, further conduit means connecting said chamber with the interior of said cylinder on one side of said piston, and valve means for controlling fluid flow through said conduit means, said valve means comprising a valve member adapted to block said inlet conduit means, a second valve member adapted to block said exhaust conduit means, a magnetic bar secured to both of said valve members, a pair of magnetic rods mounted in said cylinder with one end of each extending into said chamber and positioned adjacent said bar, a permanent magnet positioned between said rods, said rods normally attracting said bar into contact with the ends thereof to cause one of said valve members to block the conduit means it controls, a second magnetic bar mounted adjacent the other end of each of said rods, said second bars being movable into contact with said other ends of said'rods, and means for moving said second bar toward and away from said other ends of said rods, said second bar short circuiting the magnetic flux of said magnet to thereby cause said first mentioned bar to block the conduit means it controls.

4. A iiuid operated motor comprising a cylinder, a piston reciprocable within said cylinder, a piston rod iixed to said piston and extending outwardly of one end of said cylinder, a chamber formed in said one end of said cylinder on each side of said piston rod, fluid inlet conduit means leading to one portion of each of said chambers, fluid exhaust conduit means leading from another portion of each of said chambers, further conduit means leading from each chamber toI opposite sides of said piston, a magnetic bar positioned in each chamber between the respective portions thereof, valve means carried by said bar adapted to control the passage of uid through said conduit means upon movement of the respective bars toward and away from the respective portions of said chambers, a pair of spaced magnetic rods extending into each chamber, said pairs of rods being mounted in said cylinder, with the inner ends of said rods being positioned adjacent the respective bars, magnet means positioned between the rods of each pair of rods, a magnetic bar mounted adjacent the outer ends of each of said pairs of rods and on either side of saidypiston rod, and means for alternately moving the respective last mentioned bars toward and away from the respective pairs of rods, and into and out of contact with the respective pairs of rods whereby the rst mentioned bars are alternately moved into and out of contact with said rods to actuate said valve means, said second mentioned bars when in contact with the respective pairs of rods short circuiting the magnetic iiux of the respective magnet means to release the respective first mentioned bars from said inner ends of the respective pairs of rods.

5. T he fluid operated motor set forth in claim 4 wherein the last mentioned means comprises a pair of pivotally mounted rocker arms positioned on either side of said piston rod, one of the last mentioned bars being secured to one pair of adjacent ends of said rocker arms and the other of said last mentioned bars being secured to thev other pair of adjacent ends of said rocker arms,

and means for actuating said rocker larms upon predetermined movement of said piston rod whereby reciprocation of said piston rod causes pivoting movement of said rocker arms for moving the last mentioned bars toward 8 yand away from the outer ends of the respective pairs of rods.

6. The fluid operated motor set forth in claim 5 whereyin resilient means is interposed between said second mentioned bars and the respective ends of said rocker arms.

7. A device of the type described comprising a cylinder, a piston reciprocating within said cylinder, a piston rod lixed to said piston and extending outwardly of one end of said cylinder, a chamber formed in said one end of said cylinder on each side of said piston rod, iiuid inlet conduit means leading to a valve seat in one portion of each of said chambers, lluid exhaust conduit means leading from a valve seat in another portion of each of said chambers, saidvalve seats opposing each other in said chamber, further conduit means leading from each charnber to opposite sides of said piston, a magnetic bar positioned in each chamber between the said valve seats therein, each of said bars carrying valve means adapted to engage in the respective valve seats on movement of the respective bars toward the respective valve seats, means biasing the respective bars toward like valve seats, a pair of spaced magnetic rods extending into each chamber, said pairs of rods being mounted in said cylinder, with the inner ends of said rods being positioned adjacent the respective bars, magnet means positioned between the rods of each pair of rods, a magnetic bar mounted adjacent the outer ends of each of said pairs of rods, and on either side of said piston rod, a pair of rocker arms pivotally mounted on either side of said piston rod and extending between said second mentioned bars, said rocker arms being pivoted intermediate the ends thereof and being substantially perpendicular to said piston rod, means connecting the ends of said rocker arms to the respective second mentioned bars, a further arm pivoted to each rocker arm on one side of said piston rod, said further arms being connected at their ends by cross bars, said further arms being disposed substantially parallel to said piston rod, means for maintaining said further arms substantially parallel to said piston rod, said piston rod including abutment means adapted to engage said cross bars to rock said rocker arms on reciprocation of said piston rod, said rocker arms alternately moving the respective second bars into and out of contact with the outer ends of said rods, said second mentioned bars when in contact with the respective pairs 'of rods short circuiting the magnetic ilux of said magnet means to release the respective first mentioned bars from said inner ends of the respective pairs of rods. v Y

8. In a fluid operated motor having a cylinder and a double acting piston slidable therein, a piston rod attached to said piston, a pressure fluid inlet, a pressure uid exhaust, means forming a rst chamber permanently connected to said cylinder on one side of the cylinder axis,

means forming a second chamber permanently connected to said cylinder on the opposite side of said cylinder axis, both of said chambers being adapted to be connected through passageways to said pressure iluid inlet and said pressure fluid exhaust, a first double ended control valve inv said first chamber, a second double ended control valve in said second chamber, valve seats formed in each chamber and adapted to be engaged by said control Valves, magnetic means comprising a magnet for controlling the operation of each of said control valves, a control valve armature carrying each control valve and adapted to be attracted to the magnet for the control valve, and means actuated through the movement of said motor piston for controlling the operation of said magnetic means, the arrangement being such that when one of said valves is in one of its operative positions, one of its valve ends allows pressure fluid to enter said cylinder on one side of said piston and its other valve end closes said cylinder on said same side of said motor piston to exhaust, while when said other valve is in a corresponding position, one of its on the opposite side of said piston and its other valve end responding to the holes 91 ad 92) formed in the cover plate` 65. lIron pole `pieces .or rods (correspondingl to the pole pieces 93 and 94) are xed respectively in the.`

said holes in the cover plate 65 sothat their-inner ends are in the chamber 66 in the air-,motor Acylinder cover 2.`

The pole pieces are arranged directly, abovethe control valve actuating armature 65...; t

The cross beams 50 and 51 are caused to rock by the and by the engagement of gthelower, face` ofthe collar with the lower cross bar.56. Thuswhen the crossbeams are rocked in one `direction by the engagement of .the

collar 24 with the cross bar 55the.,control armature 40 engages the two .pole pieces 93 and 9.4.on.,one sidentthe axis of the air-motor cylinder, and the other-control armature 41 is lifted otf the other pole pieces- When the cross beams 50 and 51,are.rocked in the opposite direction by .theengagement of the collar: 24.Y

with the cross bar 56, thecontrol armature .41 engages the two pole pieces belowv it on the oppositeside of. ,the

air-motor cylinder axis, and the armature 40. is lifted .off f.

thepolepieces 93 and94. The armatures .40 and-..41 are guided in their up and 25 down movements by pins 98and screwed into the pole pieces. .l The two pole pieces associated with the valve-controlling armatures 62 and 65 attract the latter. when the path.

of the magnetic ux isdirected downwards.- The` force of attraction causes the .upper end 60a or61a ofthe airv control valve 60or 61 to beppullevd on to its va.lveseat69.v or 71 whilst its lower end` `60b or,6 1b ispulled ot itsseat. 77 or 80 so that the inwardow oicompressed air, say

into the top end orbottom end of theA air-motor cylinder 1, is stopped, and,thatendof-thecylinder `is connected.

to exhaust. Thus, when ,the valve controlarmature 62, is lifted against its pole pieces the. supplyof airto the...

cylinder space above the piston a is cut off .while that space is opened toexhaust through.,the. chamben79and simultaneously, upon theother `valve control armature 65 being lowered from its -polepieces, air is supp1ied to the cylinder space below the piston 5a and -that space is closed to exhaust. The reverse action, takes place when the armature 65 is lifted and .the armature 62 isA lowered. Thus, it is` only necessary to energisethepole pieces magnetically `so as to bringabout theV reversal of.

the air control needle valves L60 and `61 and,.conversely,

when most of the magnetic ux is diverted away fronr,

50 means, and means for short circuiting said magnetic tlux end of the needle valve. This ,diversion of the ,magnetic ux is brought about by` permittingcachI control armature or 41 (which acts as a short-,circuitingarmature) to rest upon the upper ends, ofthe pole pieces, above which it is arranged. This causes most `o ,f the ux to traverse the shorter` and morepermeable path through the short-circuiting` armature-and so weakens the-ux in .60 chamber between the chamber ports for-said inlet and the valve-actuating armature` 62 or 65 ,that the latter falls away from the pole pieces.,l t,

The control, or short-circuiting, armatures or bars 40 and 41 are attached to4 their actuating links ,by means of the spring-loaded screws 46 .and 41 as previously mentioned, so that when thecross beams 50and 51 are rocked, suicient energy is stored in the springs Yto cornplete the upward travel of the control armatures `as soon as their contact with the pole `pieces has been broken, thus ensuring that the mechanism cannot stall in its movement in a half-cocked condition.`

In the illustrated embodiment, .the valve armatures or bars 62 and 65 are biased away from therinner ends of the pole pieces by gravity. IOtherappropriate biasing means could be employed without departing from the` 75 said `second bar toward and away from said other ends scope of the invention,`

It will be understood thatthe air control valves and `61 could. be operated byclectrically-excited magnets instead-of by permanent magnets and that, in sucha case,` the valvereversal could becarried out by electrical 6 switching instead of the mechanical operation of shortzfcircuitingarmatures,

A packing `orsealing ring 100 is fitted in a groove in the air-motor cylinder cover 2 around thehollow cylinder 11 attached to the top end of the air-motor piston .10 rod 5, a packing or scaling ring 101 is also fitted in a groove in the air-motor pistonSa and a further packing or sealing n'ng 102 is tted in the ysaid downwardly-pra jecting .boss .3 .on the base of the air-motor cylinder around the air-motor piston rod. On each sideof each Vlli ofthe4 rings. 100, 101 .and 102 annular felt washers 103,

.20 motor. cylinder shall be properly lubricated.

:fr By removing the plug 17` from the bore of the bridge piece. 4the check valve` `lil may be inspected and by the removal of wing nuts 109 which hold the bridge piece 14 upon the above mentionedl brackets V15, the high pressure piston 13,may bewithdrawn. The high pressure cylinder21 may also be removed by unscrewing the said retaining sleeve 24 .on the hollow cylinder 1l attached to the air-motorpiston rod. Thus, all the high pressure pump components are accessible without removing the pump from the grease drum. t u A 1. Adevice of the type described comprising a cylinder, a piston reciprocable in said cylinder, means forminga valvel chamber, inlet. conduit. means leading to said chamber, exhaust conduit means leading from said charn- "iberysaid inlet and exhaust conduit .means terminating in opposed valve seats formed in said chamber, further cont 45 otherA of said valve seats in opposition to the action of saidbiasing means, said magneticlmeans including magnetietiux conducting means. positioned to attract said bar, magnet means for.. supplying sucient magnetic ux to said tux conducting means to overcome said biasing to `permit said biasing means to draw said bar toward said one .of said valve seats.

2..In combination, -a cylinder, a piston reciprocable in said cylinder, saidcylinder having a chamber formed 55 in one of the walls thereof, uid inlet conduit means lead-- king tosaid chamber, uid exhaust conduit `means leading from said chamber, further-conduit means connecting said chamber `with the interior of said cylinder on one side,of said piston, amagneticbar positioned in said .55 rods mounted in said cylinder with one end of each extending into said chamber and positioned adjacent said bar, means `biasing said bar away from said one ends of said rods, magnet means positioned between said rods, said rods. magnetically attracting said bar into contact with said onetends thereof to cause one of said valve members to block the chamber port it controls, a second magnetic bar mounted `adjacent-the other ends of each of said rods, said second bar being movable into contact with said other ends of said rods, and means for moving closes said cylinder on said opposite side of said piston to exhaust, a reversal of flow of pressure fluid taking place when each valve is in its second operative position, said magnets comprising permanent magnets, each of which includes a set of pole pieces interposed between each magnet and its respective control valve armature, said armature being attracted toward said pole pieces in a direction to close said cylinder on opposite sides of said piston to pressure fluid admission and to open the same to exhaust, and means for diverting most of the magnetic flux away from said pole pieces so that said control valve armatures will fall away from said pole pieces.

9. A device as claimed in claim 8 wherein said ux diverting means comprises a short circuiting armature associated with each set of pole pieces.

10. A device as claimed in claim 9 wherein said means actuated through the movement of said piston comprises a rocker mechanism connected to said short circuiting armatures, and means for oscillating said rocker mechanism upon reciprocation of said piston, the arrangement being such that when said piston is moved in one direction, said rocker mechanism is oscillated in one direction and one of said armatures is caused to short circuit one of said sets of pole pieces and the other armature is moved out of short circuiting position, reverse movement of the armatures taking place when said rocker mechanism is oscillated in the opposite direction.

l References Cited in the le of this patent UNITED STATES PATENTS 1,229,443 Hall et al. June 12, 1917 1,447,962 Callaghan Mar. 13, 1923 2,312,857 Woelfer Mar. 2, 1943 2,357,029 Smith Aug. 29, 1944 FOREIGN PATENTS 474,072 Great Britain Oct. 20, 1937 

